The majority of personality scales in use today were developed using dominance model，which assume that respondents with higher trait levels exhibit higher item scores than do those with low trait levels and that the probability of observing a high item score increases monotonically as the distance between person and item locations increases.shows that the probability of a positive response increases as a person lies increasingly distant and above the item’s location.But as personality assessment technology developed，the reliance on dominance assumptions and associated scale construction procedures has been queried.Researchers begin to pay attention to the unfolding model，which assume people respond positively to items that have locations similar to their own.In probabilistic terms，as the distance between a respondent’s location on the trait continuum(called his or her ideal point)and the item’s location increases，the probability of endorsing the item decreases.As a more mature model，GGUM has been used in many personality assessment fields，but still need to undertake large-scale test to accumulate experience of evaluation and forecast validity，establish an acknowledged psychometric norm，and continue to explore corresponding theory and simple statistical procedure.